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authorJohan Hovold <jhovold@gmail.com>2010-08-04 15:45:57 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-13 13:31:01 -0700
commit4a561f2ed8e6e5c428bae18af3f48045211add08 (patch)
treef94ecea674295ce62a6c0908d6724c469004a9c9
parent8762dc2878fcdab3a3d71502c42e5923c79e8086 (diff)
downloadlinux-2.6.34-ux500-4a561f2ed8e6e5c428bae18af3f48045211add08.tar.gz
USB: serial: fix stalled writes
commit b58af4066d240b18b43f202e07b9ec7461d90b17 upstream. As David VomLehn points out, it was possible to receive an interrupt before clearing the free-urb flag which could lead to the urb being incorrectly marked as busy. For the same reason, move tx_bytes accounting so that it will never be negative. Note that the free-flags set and clear operations do not need any additional locking as they are manipulated while USB_SERIAL_WRITE_BUSY is set. Reported-by: David VomLehn <dvomlehn@cisco.com> Tested-by: David VomLehn <dvomlehn@cisco.com> Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/serial/generic.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index a817ced8283..ca92f67747c 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -208,18 +208,23 @@ retry:
urb->transfer_buffer_length = count;
usb_serial_debug_data(debug, &port->dev, __func__, count,
urb->transfer_buffer);
+ spin_lock_irqsave(&port->lock, flags);
+ port->tx_bytes += count;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ clear_bit(i, &port->write_urbs_free);
result = usb_submit_urb(urb, GFP_ATOMIC);
if (result) {
dev_err(&port->dev, "%s - error submitting urb: %d\n",
__func__, result);
+ set_bit(i, &port->write_urbs_free);
+ spin_lock_irqsave(&port->lock, flags);
+ port->tx_bytes -= count;
+ spin_unlock_irqrestore(&port->lock, flags);
+
clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
return result;
}
- clear_bit(i, &port->write_urbs_free);
-
- spin_lock_irqsave(&port->lock, flags);
- port->tx_bytes += count;
- spin_unlock_irqrestore(&port->lock, flags);
/* Try sending off another urb, unless in irq context (in which case
* there will be no free urb). */